Most land vehicles, such as automobiles, have a spare tire that is stored on board in case one of the main tires springs a leak and becomes unusable. These spare tires are often carried for months, or even years, without being needed. During this period of inactivity, most spare tires are not monitored. Over time, these tires tend to lose air pressure. Thus, when a spare tire is needed, a user often finds that tire to be inoperable because its pressure is too low. Thus, many users do not find out that the spare tire needs air until it is too late.
For this reason, the art includes several devices for monitoring the air pressure in spare tires. While effective, these devices are often difficult to calibrate thereby making their accuracy, and hence, their effectiveness, suspect. The need for calibration is especially evident since people want their spare tires inflated to levels that suit their individual needs. For example, one person may use their vehicle only for city driving and will be close to filling stations during most driving times. This person need not have a spare tire that is fully inflated as only a short drive will be necessary for the spare tire. On the other hand, however, some people use their vehicles primarily for road driving. In such conditions, a filling station may be many miles away in the event a spare tire is needed. Therefore, a person using their vehicle for road driving may require their spare tire to be inflated to nearly optimum pressure as that tire may be needed for many miles. Still further, if the use of a vehicle changes from primarily road to primarily city driving as may occur if a new car is purchased to replace another car, the air pressure stored in the spare tire may be changed with the expected change in driving conditions.
Therefore, there is a need for a spare tire air pressure monitoring system that can be calibrated, and can be calibrated in situ.
Another drawback of many known devices is the difficulty in attaching the overall system to the spare tire. Thus, some people will not use the monitor because it is too much trouble to attach to and detach from the tire;
Therefore, there is a need for a spare tire air pressure monitoring system that is easily attached to and detached from a spare tire.
Yet another drawback to many known warning devices is the distraction that they can produce when they are alerting the vehicle driver that the air pressure in the spare tire is low. That is, once air pressure in the spare tire drops below the preset level, the low pressure signal is activated, but remains activated until the sensor is actually disconnected in some manner. This can distract a driver. Any distraction to the driver should be avoided as being undesirable.
Therefore, there is a need for a spare tire air pressure monitoring system which activates a low pressure signal only at certain times, which can be selected to adequately alert the driver that the spare tire air pressure is low, yet will not do so in a manner that may unduly distract the driver when he or she should not be distracted.
Since many spare tires are stored in small areas, the spare tire air pressure monitor should be small enough to be attached to a spare tire being stored in a small area.
Therefore, there is a need for a spare tire air pressure monitoring system that can be attached to a spare tire that is stored in a very small and confined area.